1. Field of the Invention
This invention pertains in general to the field of mining and, in particular, to a novel device and method for mining slurryable, shallow mineral deposits with earthy overburden in a longwall fashion.
2. Description of the Prior Art
Surface mining is and has historically been employed to recover stratified minerals under overburden to economic depths. Underground mining is traditionally employed when overburden depths exceed those economically removable by surface mining or when major surface disturbance is unacceptable.
Prior inventions have been patented for longwall mining of reserves using trenched entry where overburden is sufficiently competent to bridge over longwall shearing and conveying equipment and where floor strata are competent to withstand mining stresses. (See Simpson, U.S. Pat. No. 4,017,122.) Simpson does not accommodate soft, plastic, fluid, loose, unstable, clayey, sandy, dirt, soil, or similar (earthy) ground conditions often encountered in mining shallow ore deposits. Earthy conditions can allow the mine roof to fall ahead of shield supports or allow the floor to heave up behind the face conveyor ahead of the shield pontoons. This creates safety hazards, dilution of ores, and expensive control installation.
The present invention provides a means for mining slurryable ore reserves where overburden is earthy. Floor conditions are also reduced to being an insignificant issue.